Combined optical sight and center punch



Dec. 9, 1969 J. K. SAMQAT 3,482,324

COMBINED OPTICAL SIGHT AND CENTER PUNCH Filed Dec. 11, 1967 2Sheets-Sheet 1 Dec. 9, 1969 J. K. SAMHAT COMBINED OPTICAL SIGHT ANDCENTER PUNCH 2 Sheets-Sheet 2 Filed Dec. 11, 1967 QWY J46! 4 54MA447' IN VENTOR.

BY 6 /@z United States Patent Int. Cl. 1326f 1/32; G01b /14 US. Cl.33-189 1 Claim ABSTRACT OF THE DISCLOSURE A combined optical sight andcenter punch which includes a base member that slides about on thesurface of a work piece, having a centrally located rigid transparentsighting body that permits the operator to view the surface of the workpiece therethrough, a pair of locating cross-hairs marked on the lowerend surface of the sighting body, a plunger which is vertically disposedin a central opening in the sighting body, and a retracting springsecured to the upper end of the plunger; the operation being such thatwhen the upper extremity of the plunger is struck by a hammer a sharppoint that is formed on the lower end of the plunger makes a punch markon the surface of the work piece, and the spring then returns theplunger upward to its normal position in which the sharpened end of theplunger is elevated somewhat above the surface of the work piece.

RELATED APPLICATION The present application is a continuation-in-part ofmy prior copending application Ser. No. 636,140 filed May 4, 1967, nowabandoned.

BACKGROUND OF INVENTION In metal layout work it is well know to scribeperpendicular lines on the surface of the metal so that the intersectionof the lines defines a predetermined point, and then to make a punchmark in the metal surface at the point of intersection of the lines. Thepunch mark is then used to establish the center point for a punch ordrill which forms an opening in the work piece whose center thencoincides with the point where the punch mark had been made.

In some instances this technique is used in the precision layout of asingle work piece, for forming holes and bends in the metal as arerequired. In the great majority of cases, however, the precision layoutis applied to a single metal work piece, which is used as a template forthe subsequent fabrication of other units on a mass production basis.Each punch mark location on the template is then generally translatedinto a standard size hole, such as 4; inch, which is then used for thepurpose of transferring the point location information to the productionwork pieces.

In the prior art it has been known to utilize an easily movable, handoperated center punch for the purpose of making such punch marks in thecourse of precision layout work. It has also been known to use opticaldevices for more precisely locating the position where a punch mark isto be made. However, no convenient device has been availablewhichperforms both the optical sighting function and the punch markingfunction.

Therefore, the object and purpose of the present invention is to providea combined optical sight and center punch device, for use in precisionmetal layout work, which is economical to manufacture and convenient touse.

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DRAWING SUMMARY FIGURE 1 is a perspective view of a presently preferredembodiment of the invention, showing its application to a work piece;

FIGURE 2 is a vertical cross-sectional view taken on the line 2-2 ofFIGURE 1;

FIGURE 3 is a top plan view of the instrument of FIGURE 1;

FIGURE 4 is an enlarged fragmentary cross-sectional view showing thepunching operation of the instrument;

FIGURE 5 is a vertical cross-sectional view of an alternate form of thedevice; and

FIGURE 6 is a vertical cross-sectional view of still another form of thedevice.

PREFERRED EMBODIMENT Reference is now made to FIGURES 1 to 4, inclusive,illustrating the preferred embodiment of the invention.

A work piece 10 which is typically a fiat sheet of metal has a set ofhorizontal lines 12 and a set of vertical lines 13 scribed thereon, theintersections of the lines being points whose locations must beprecisely determined during the course of the layout work. As best seenin FIGURE 1 the instrument 20 of the present invention has been used formaking punch marks 14 at these line intersections on the work piece. Thestructure of the instrument 20 will first be described, and thereafterits mode of operation and usage will be described.

The instrument 20 includes, broadly speaking, a metal base member 25, arigid transparent optical sighting body 35, a metal plunger 45, and aresilient supporting wire 55. The functions of base member 25 are tosupport the plunger 45 in a desired position relative to the work piece10, and to provide a secure alignment of the plunger during the timewhen a punch mark is being made by the plunger. Base member 25 isprovided with a smooth, precisely flat undersurface 26, whichconveniently slides as desired on the upper surface 11 of work piece 10,with proper alignment being assured by the relatively heavy weight ofthe base member. While the base member 25 is illustrated as being ofcylindrical configuration it could equally well be cubical, hexagonal,or of almost any other desired configuration. A vertical central well 27is formed in the base member 25, which extends through the entirethickness of the member. Central well 27 is preferably cylindrical asindicated, and receives the rigid optical sighting body 35 in a pressfit relationship therein, so as to firmly retain the sighting body 35 inits desired position.

The sighting body 35 in turn has a central plunger opening 36 formedtherein, the plunger opening being preferably also of cylindricalconfiguration as shown, and extending through the entire vertical lengthof the sighting body 35. The fixed vertical position of sighting body 35relative to base member 25 is such that the lower end surface 37 ofsighting body 35 is preferably elevated somewhat above the undersurface26- of the base member. A pair of cross-hairs 38, 39, shown only inFIGURE 3, are scribed on the lower end surface 37. Both the lowerendsurface 37 and also the upper end surface 41 of the sighting body 35are, in the preferred embodiment of FIGURES 1 to 4, flat surfaces.

Plunger 45 is disposed within the plunger opening 36 in a verticallyslidable relationship, being fitted loosely enough to have a relativelyeasy sliding action but tightly enough to ensure a precise verticalalignment of its longi tudinal axis. A sharp point 46 is formed on the,lower end of plunger 45, and since the point 46 is located at thehorizontal center of the lower end of the plunger, and since the plungeropening and plunger are both concentric to the sighting body 35, ittherefore follows that the point 3 46 is also located at the horizontalcenter of the lower end of the sighting body. As clearly shown in FIGURE3 the cross-hairs 38, 39 are located so that (if extended) theyintersect at the horizontal center of the sighting body, and hence, atthe precise location of the plunger point 46.

Plunger 45 has its upper extremity 48 exposed and is adapted to be hitwith a hammer for selectively driving it downward in order to form apunch mark 14 by means of the plunger point 46. A lateral opening 47 isformed in the plunger somewhat below its upper extremity, and aretaining wire 55 extends therethrough. The retaining wire 55 ispreferably a short length of piano wire which has been bent into anarcuate configuration. The central section 56 of the wire which passesthrough plunger opening 47 being horizontally disposed while the twoends are progressively bent downward, with the extreme ends 57 of thewire 55 being disposed at an angle of approximately 45 to thelongitudinal axis of the plunger. A pair of openings 29 are formed inthe upper surface 28 of base member 25, on opposite sides of the centralwell 27, and these openings are relatively shallow and have a widthwhich is significantly greater than the thickness of wire 55, so thatthe ends of the wire are loosely received in the openings. The openings29, like the wire ends 57, are disposed at an angle of approximately 45relative to the longitudinal axis of plunger 45.

In operation, the rigid sighting body 35 is firmly maintained inposition within the central well 27 of base member 25, and the relativepositions of those two members are not disturbed. Base member 25 ismoved about wherever desired on the surface of work piece 10 so that theoperator may, by looking vertically downward through the sighting body35, see the crosshairs 38, 39 and align them with an intersecting pairof the lines 12, 13. Insertion of the ends 57 of the retaining wire 55in the openings 29 causes the wire 55 to remain under stress, and in itsfully arched position as best seen in FIGURE 2 it holds the plunger 45at such an elevation that the plunger point 46 is somewhat elevatedabove the upper surface 11 of work piece 10. When the operator hasaligned crosshairs 38, 39 with intersecting lines 12, 13, he thenstrikes the upper extremity 48 of the plunger with a hammer, depressingthe plunger downward by approximately 7 s of an inch so as to form apunch mark 14 in the surface of work piece 10. The punching action isillustrated in FIGURE 4 wherein the arrow 49 schematically indicates thedownward force exerted by the hammer. After the punch mark 14 is formed,the support wire 55, which was temporarily depressed at its lateralcenter portion 56, exerts an upper force so as to return the plunger toits normal position as shown in FIGURE 2.

The optical sighting body 35 could be made of glass, however, it ispreferred to utilize a synthetic organic plastic material for thispurpose. The cross-hairs 38, 39 are made in a conventional manner byforming shallow troughs on the undersurface 37 of the optical body andfilling the shallow troughs with a coloring material. 9

FIRST ALTERNATE FORM FIGURE illustrates a first alternate form of theinvention. In the embodiment of FIGURE 5 the base member 25 and supportwire 55 are exactly the same as already described. Optical sighting body35a is generally the same as previously described and performs generallythe same function, however, its upper end surface 41a is formed with asomewhat concave configuration, and its lower end surface 37a is alsoformed with a somewhat concave configuration. Plunger 45a is generallythe same as plunger 45 except that its sharp point 46a is an elongatedcone, so'that the extremity of the point is more clearly visible. Theinclined curve surfaces 41a and 37a perform the function of bendingthelight rays in a well known manner, so that the area' of vision of theviewer who is looking down from "above the instrument is not limited tothe surface of the work piece that l es immed a y be e h the opticalsighting body 35, but also extends to the surface that lies beneath theplunger 45a. In the embodiment of FIGURE 5 the curvature of concavelower end surface 37a of sighting body 35a is made much greater than thecurvature of the concave upper surface 41a. It then becomes possible forthe operator to see the extremity of the punch point 46a at theintersection of the cross-hairs 38, 39.

SECOND ALTERNATE FORM FIGURE 6 illustrates a second alternate form ofthe invention. The reference numbers are generally the same as in thepreferred embodiment but are raised by 100. In the embodiment of FIGURE6 there is no separate optical sighting member 35; instead the basemember is made of rigid transparent plastic and has a central portionWithin which the plunger well 136 is formed. The lower flat surface 137of the base member central portion 135 carries cross-hairs 138, 139, inthe manner previously illustrated. A helical spring 155 is carried onthe upper end of plunger 145 and is held between snap ring 129, securedto the plunger, and the upper surface of base member 125. The upperexterior wall surface of the base member 125 is knurled as indicated at140 for convenience in handling.

Having described the invention, what is claimed as new in support ofLetters Patent is:

1. A combined optical sight and center punch for making a punch mark onthe flat surface of a workpiece at the precise point of intersection ofa pair of perpendicular lines scribed thereon, comprising:

a rigid, optically transparent base member integrally formed of plasticmaterial, having a generally cylindrical shape with its length beingshorter than its diameter and with the lower end thereof providing asmooth, precisely flat undersurface adapted to slide about on the flatsurface of the workpiece, said base member having a cylindrical plungeropening centrally formed therein which opening extends through theentire vertical length of said base member in precisely perpendicularrelationship to said undersurface thereof, said base member also havinga central bottom surface portion surrounding said central plungeropening which is recessed above said precisely fiat undersurface, andhaving a perpendicular pair of cross-hairs carried on said centralbottom surface portion and being so disposed that if extended theirpoint of intersection would lie at the horizontal center of said plungeropening;

an elongated cylindrical plunger slidingly disposed within said plungeropening, having a sharp point formed on its lower end at the horizontalcenter of said plunger opening, being of sufficient length to extend asignificant distance above the upper end of said base member, having aflat upper end adapted to be struck by a hammer, and having acircumferential groove formed near its upper end;

a snap ring carried by said circumferential groove of said plunger;

and a helical spring concentrically disposed on the upper end portion ofsaid plunger between said snap ring and the upper end surface of saidbase member, said plunger being freely removable from said base memberand the length of said spring being sufficient to normally support saidplunger at an elevation such that said sharp point thereof is suspendedsomewhat above the elevation of said base member undersurface;

- the upper end of the circumferential wall surface of said base memberbeing knurled for convenience in handling;

whereby said base member may be slidingly positioned on the flat surfaceof the workpiece without direct contact between said cross-hairs and theworkpiece su ace, the alignment of sa d c oss-h i s w th e pair ofperpendicular lines on the workpiece may be visually determined at fourseparate points about the periphery of said plunger, and the upperextremity of said plunger may then be struck to cause said sharp pointthereof to make an impression in the workpiece surface at theintersection of the perpendicular lines thereon.

References Cited UNITED STATES PATENTS 6 2,934,829 5/1960 Bohn 33-1893,230,631 1/1966 Skidmore 33189 FOREIGN PATENTS 5 207,580 2/ 1960Austria.

636,815 5/1950 Great Britain.

OTHER REFERENCES American Machinist Magazine, p. 126; Jan. 13, 1958.

10 ROBERT C. RIORDON, Primary Examiner J. C. PETERS, Assistant ExaminerUS. Cl. X.R. 30368

